<!DOCTYPE html>
<svg>
  <mask id="m">
    <g visibility="hidden">
      <rect width="100" height="100" fill="white" visibility="visible"/>
      <rect width="200" height="100" fill="white"/>
    </g>
  </mask>
  <rect width="200" height="100" fill="green" mask="url(#m)"/>
</svg>
